Optical device for augmented reality having improved light efficiency

ABSTRACT

Disclosed herein is an optical device for augmented reality having improved light efficiency. The optical device includes: a reflective means configured to transfer augmented reality image light to the pupil of a user by reflecting the augmented reality image light toward the pupil; and an optical means adapted such that the reflective means is embedded and disposed therein, and configured to transmit at least part of real object image light therethrough toward the pupil of the user. The optical means includes a first surface and a second surface. The reflective means includes a plurality of reflective units having a size of 4 mm or less that are embedded and arranged inside the optical means. At least two reflective units of the plurality of reflective units are arranged closer to the second surface of the optical means as the distance from the image output unit increases.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.17/024,503, filed on Sep. 17, 2020. Further, this application claims thebenefit of Korean Patent Application No. 10-2019-0114729 filed on Sep.18, 2019 and No. 10-2019-0173543 filed on Dec. 24, 2019, which arehereby incorporated by reference herein in its entirety.

BACKGROUND 1. Technical Field

The present invention relates generally to an optical device foraugmented reality, and more particularly to an optical device foraugmented reality, in which the light efficiency of the augmentedreality image light output from an image output unit and transmitted tothe pupil is improved.

2. Description of the Related Art

Augmented Reality (AR) refers to technology that superimposes a virtualimage, generated by a computer or the like, on a real image of the realworld and then provides a resulting image, as is well known.

In order to implement augmented reality, there is required an opticalsystem that allows a virtual image, generated by a device such as acomputer, to be superimposed on an image of the real world and aresulting image to be provided. As such an optical system, there isknown a technology using an optical means such as a prism for reflectingor refracting a virtual image using a head-mounted display (HMD) or aglasses-type device.

FIGS. 1 and 2 show an example of an optical system that is used in aconventional apparatus for implementing augmented reality.

Referring to FIG. 1 , a configuration is employed to allow augmentedreality image light for the provision of a virtual image to be outputfrom a display device (not shown), to be reflected from the innersurface of an optical means, and then to enter an eye box, which is aregion where the pupil of a user is located. In this case, not all theaugmented reality image light output from the inner surface (the exitpupil) of the optical means can enter the eye box, as shown in FIG. 1 ,and thus unused light is present. This leads to a factor thatdeteriorates light efficiency.

As shown in FIG. 2 , when total reflection occurs inside the opticalmeans, light in all directions is output from all locations of the exitpupil, so that part of the augmented reality image light entering theoptical means appropriately enters the eye box (indicated by O) whereaspart of the augmented reality image light is output in a direction otherthan the direction of the eye box (indicated by X).

As described above, the conventional apparatus for implementingaugmented reality is problematic in that part of the augmented realityimage light output from the image output unit is not transferred to theeye box, and thus this acts as a factor that decreases the lightefficiency at which augmented reality image light is transferred to thepupil.

PRIOR ART DOCUMENT

Patent document 1: Korean Patent No. 10-1660519 (published on Sep. 29,2016)

SUMMARY

The present invention has been conceived to overcome the above-describedproblems, and an object of the present invention is to provide anoptical device for augmented reality, in which the light efficiency ofthe augmented reality image light transferred to an eye box is improved.

Another object of the present invention is to provide an optical devicefor augmented reality, in which a reflective means for transferring theaugmented reality image light, output from an image output unit, to thepupil is formed a curved arrangement structure close to a C shape, sothat the light efficiency of the augmented reality image lighttransferred to an eye box is improved.

According to an aspect of the present invention, there is provided anoptical device for augmented reality having improved light efficiency,the optical device comprising: a reflective means configured to transferaugmented reality image light, which is image light corresponding to animage for augmented reality output from an image output unit, to a pupilof an eye of a user by reflecting the augmented reality image lighttoward the pupil, thereby providing the image for augmented reality tothe user; and an optical means adapted such that the reflective means isembedded and disposed therein, and configured to transmit at least partof real object image light, which is image light output from a realobject, therethrough toward the pupil of the eye of the user; whereinthe optical means includes a first surface through which the augmentedreality image light reflected from the reflective means and at leastpart of the real object image light go toward the pupil of the user anda second surface being opposite to the first surface and into which thereal object image light enters; wherein the reflective means includes aplurality of reflective units having a size of 4 mm or less that areembedded and arranged inside the optical means to transfer the augmentedreality image light, transferred to the reflective means, to the pupilof the user by reflecting the augmented reality image light; and whereinat least two reflective units of the plurality of reflective units arearranged closer to the second surface of the optical means as a distancefrom the image output unit increases.

Preferably, the augmented reality image light output from the imageoutput unit is directly transferred to the reflective means through aninside of the optical means, or is totally reflected from an innersurface of the optical means at least once and then transferred to thereflective means.

Further, each of the plurality of reflective units may be inclined at anangle of 45 degrees or less with respect to a forward direction from acenter of the pupil of the user.

Furthermore, a plurality of reflective means may be formed, and when theoptical device for augmented reality is placed in front of the pupil ofthe user, assuming that a forward direction from the pupil is referredto as an x axis, any one of line segments being parallel to a verticalline between the image output unit and the x axis along the x axis andpassing between the first and second surfaces of the optical means isreferred to as an y axis and a line segment perpendicular to both the xaxis and the y axis is referred to as an z axis, then each of theplurality of reflective means is arranged at intervals in parallel witheach other along a z-axis direction.

The reflective means may be arranged such that each of reflective unitsincluded in each of the reflective means is located along a virtualstraight line parallel to the z axis along with any one of reflectiveunits included in adjacent reflective means.

The reflective means may be arranged such that each of reflective unitsincluded in each of the reflective means is prevented from being locatedalong a virtual straight line parallel to the z axis along with any oneof reflective units included in adjacent reflective means.

Preferably, the optical device for augmented reality is placed in frontof the pupil of the user, assuming that a forward direction from thepupil is referred to as an x axis, any one of line segments beingparallel to a vertical line between the image output unit and the x axisalong the x axis and passing between the first and second surfaces ofthe optical means is referred to as an y axis and a line segmentperpendicular to both the x axis and the y axis is referred to as an zaxis, then each of the plurality of reflective units may be formed inbar shapes extending in a z-axis direction.

Further, at least some of the reflective units may have a differentsize.

Also, at least some of the reflective units may be arranged at intervalsdifferent from intervals at which other reflective units are arranged.

Furthermore, at least some of the reflective units may be composed of atleast any one of half mirrors, refractive elements, and diffractiveelements.

Further, at least some of the reflective units may have a surface coatedwith a material that absorbs light without reflecting light, wherein thecoated surface is opposite surface to a surface reflecting the augmentedreality image light.

Further, at least some of the reflective units may have surfaces formedas curved surfaces.

Further, the surfaces formed as curved surfaces may be concave towardthe first surface of the optical means or convex toward the firstsurface of the optical means.

Preferably, when the reflective units are placed in front of the pupilof the user, assuming that a forward direction from the pupil isreferred to as an x axis, any one of line segments being parallel to avertical line between the image output unit and the x axis along the xaxis and passing between the first and second surfaces of the opticalmeans is referred to as an y axis and a line segment perpendicular toboth the x axis and the y axis is referred to as an z axis, then atleast some of the reflective units may be formed such that a lengththereof in a z-axis direction is formed to be longer than a lengththereof in an x-axis direction or such that a length thereof in a y-axisdirection is formed to be longer than a length thereof in the z-axisdirection.

Further, the reflective units formed such that the length thereof in thez-axis direction is formed to be longer than the length thereof in thex-axis direction or such that the length thereof in the y-axis directionis formed to be longer than the length thereof in the z-axis directionmay have surfaces formed as concave toward the first surface of theoptical means or as convex toward the first surface of the opticalmeans.

According to another aspect of the present invention, there is providedan optical device for augmented reality having improved lightefficiency, the optical device comprising: a reflective means configuredto transfer augmented reality image light, which is image lightcorresponding to an image for augmented reality output from an imageoutput unit, to a pupil of an eye of a user by reflecting the augmentedreality image light toward the pupil, thereby providing the image foraugmented reality to the user; and an optical means adapted such thatthe reflective means is embedded and disposed therein, and configured totransmit at least part of real object image light, which is image lightoutput from a real object, therethrough toward the pupil of the eye ofthe user; wherein the optical means includes a first surface throughwhich the augmented reality image light reflected from the reflectivemeans and at least part of the real object image light go toward thepupil of the user, and a second surface being opposite to the firstsurface and into which the real object image light enters; wherein thereflective means includes a plurality of reflective units having a sizeof 4 mm or less that are embedded and arranged inside the optical meansto transfer the augmented reality image light, transferred to thereflective means, to the pupil of the user by reflecting the augmentedreality image light; wherein the reflective means includes a firstreflective unit group comprising reflective units embedded and arrangedinside the optical means so that the reflective units are arrangedcloser to the first surface of the optical means as a distance from theimage output unit increases, and a second reflective unit groupcomprising reflective units embedded and arranged inside the opticalmeans so that the reflective units are arranged farther from the firstsurface of the optical means as a distance from the image output unitincreases; and wherein the first reflective unit group and the secondreflective unit group are arranged such that a distance between thesecond reflective unit group and the image output unit is larger than adistance between the first reflective unit group and the image outputunit.

Preferably, the augmented reality image light output from the imageoutput unit may be directly transferred to the reflective means throughan inside of the optical means, or may be totally reflected from aninner surface of the optical means at least once and then transferred tothe reflective means.

Further, each of the plurality of reflective units may be inclined at anangle of 45 degrees or less with respect to a forward direction from acenter of the pupil of the user.

Preferably, a plurality of reflective means may be formed; and when theoptical device for augmented reality is placed in front of the pupil ofthe user, assuming that a forward direction from the pupil is referredto as an x axis, any one of line segments being parallel to a verticalline from the image output unit to the x axis along the x axis andpassing between the first and second surfaces of the optical means isreferred to as an y axis and a line segment perpendicular to both the xaxis and the y axis is referred to as an z axis, then the each of theplurality of reflective means is arranged at intervals in parallel witheach other along a z-axis direction.

Further, the reflective means may be arranged such that each ofreflective units included in each of the reflective means is locatedalong a virtual straight line parallel to the z axis along with any oneof reflective units included in adjacent reflective means.

Further, the reflective means may be arranged such that each ofreflective units included in each of the reflective means is preventedfrom being located along a virtual straight line parallel to the z axisalong with any one of reflective units included in adjacent reflectivemeans.

Furthermore, when the optical device for augmented reality is placed infront of the pupil of the user, assuming that a forward direction fromthe pupil is referred to as an x axis, any one of line segments beingparallel to a vertical line between the image output unit and the x axisalong the x axis and passing between the first and second surfaces ofthe optical means is referred to as an y axis and a line segmentperpendicular to both the x axis and the y axis is referred to as an zaxis, then each of the plurality of reflective units may be formed inbar shapes extending in a z-axis direction.

Further, at least some of the plurality of reflective units may becomposed of at least any one of half mirrors, refractive elements, anddiffractive elements.

Furthermore, at least some of the reflective units may have a surfacecoated with a material that absorbs light without reflecting light,wherein the coated surface is opposite surface to a surface reflectingthe augmented reality image light.

Furthermore, at least some of the plurality of reflective units may havesurfaces formed as curved surfaces.

Furthermore, when the optical device for augmented reality is placed infront of the pupil of the user, assuming that a forward direction fromthe pupil is referred to as an x axis, any one of line segments beingparallel to a vertical line from the image output unit to the x axisalong the x axis and passing between the first and second surfaces ofthe optical means is referred to as an y axis and a line segmentperpendicular to both the x axis and the y axis is referred to as an zaxis, then at least some of the plurality of reflective units may beformed such that a length thereof in a z-axis direction is formed to belonger than a length thereof in an x- or y-axis direction or such that alength thereof in the x- or y-axis direction is formed to be longer thana length thereof in the z-axis direction.

Further, the reflective units may have surfaces formed as concave towardthe first surface of the optical means or as convex toward the firstsurface of the optical means.

Preferably, a plurality of reflective means are formed; and when theoptical device for augmented reality is placed in front of the pupil ofthe user, assuming that a forward direction from the pupil is referredto as an x axis, any one of line segments being parallel to a verticalline from the image output unit to the x axis along the x axis andpassing between the first and second surfaces of the optical means isreferred to as an y axis and a line segment perpendicular to both the xaxis and the y axis is referred to as an z axis, then there may be atleast one reflective means that has a different distance to the firstsurface of the optical means.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features, and advantages of the presentinvention will be more clearly understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIGS. 1 and 2 show an example of an optical system that is used in aconventional apparatus for implementing augmented reality;

FIG. 3 is a diagram showing an optical device 100 for augmented realitysuch as that disclosed in patent document 1;

FIG. 4 is a diagram showing an optical device for augmented realityhaving improved light efficiency according to a first embodiment of thepresent invention;

FIG. 5 is a diagram illustrating a structure in which reflective unitsare arranged;

FIG. 6 is a perspective view of the optical device for augmentedreality, which is illustrated in FIGS. 4 and 5 ;

FIG. 7 shows diagrams illustrating the effects of structures in whichreflective units are arranged;

FIGS. 8 and 9 are diagrams illustrating the inclination angles ofreflective units;

FIGS. 10 and 11 are diagrams illustrating the overall operation of theoptical device for augmented reality according to the first embodimentof the present invention;

FIG. 12 is a diagram showing the configuration of an optical device foraugmented reality according to a modification of the first embodiment ofthe present invention;

FIG. 13 is a diagram showing the configuration of an optical device foraugmented reality according to another modification of the firstembodiment of the present invention;

FIG. 14 is a diagram showing the configuration of an optical device foraugmented reality according to still another modification of the firstembodiment of the present invention;

FIG. 15 is a diagram illustrating a state in which the surfaces ofreflective units are formed as curved surfaces;

FIG. 16 is a diagram showing another example of the curved surface shapeof the reflecting units;

FIG. 17 is a diagram showing an optical device for augmented realityaccording to a second embodiment of the present invention;

FIG. 18 is a diagram illustrating the arrangement structure of thereflective units illustrated in FIG. 17 ;

FIG. 19 is a perspective view of the optical device for augmentedreality according to the second embodiment of the present invention;

FIG. 20 is a diagram illustrating the effect of the arrangementstructure of the reflective units of the optical device for augmentedreality according to the second embodiment of the present invention;

FIGS. 21 to 23 are diagrams illustrating the numbers of times thataugmented reality image light is totally reflected by an optical means;

FIGS. 24 and 25 are diagrams illustrating the overall operation of theoptical device for augmented reality;

FIG. 26 is a diagram showing the configuration of an optical device foraugmented reality according to a modification of the second embodimentof the present invention;

FIG. 27 is a diagram showing the configuration of an optical device foraugmented reality according to another modification of the secondembodiment of the present invention;

FIG. 28 is a diagram showing the configuration of an optical device foraugmented reality according to still another modification of the secondembodiment of the present invention;

FIGS. 29 to 31 are diagrams showing the configuration of an opticaldevice for augmented reality according to still another modification ofthe second embodiment of the present invention;

FIG. 32 is a diagram showing the configuration of an optical device foraugmented reality according to still another modification of the secondembodiment of the present invention;

FIG. 33 is a diagram showing the configuration of an optical device foraugmented reality according to still another modification of the secondembodiment of the present invention; and

FIG. 34 is a diagram showing the configuration of an optical device foraugmented reality according to still another modification of the secondembodiment of the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention will be described in detail belowwith reference to the accompanying drawings.

First, the basic principle of the present invention will be brieflydescribed with reference to patent document 1.

The technology described in patent document 1 as the prior art isintended to overcome the problems of the conventional apparatus forimplementing augmented reality using an existing optical system asfollows.

That is to say, the conventional apparatus for implementing augmentedreality is problematic in that it is inconvenient for a user to wearbecause the structure thereof is complicated and thus the weight andvolume thereof are increased and in that the manufacturing cost thereofis high because the manufacturing process thereof is also complicated.

Furthermore, the conventional apparatus for implementing augmentedreality has a limitation in that a virtual image is out of focus when auser changes a focal distance while gazing at the real world. In orderto overcome this problem, there have been proposed a technology using aconfiguration such as a prism capable of adjusting the focal distance ofa virtual image and a technology electrically controlling a variablefocus lens capable of changing the focal distance of a virtual image inresponse to a change in a focal distance to the real world. However,these technologies also have a problem in that to adjust the focaldistance of a virtual image, a user needs to perform a separateoperation, or hardware such as a separate physical device or processorand software are required.

Accordingly, through patent document 1, the applicant of the presentinvention proposed an apparatus for implementing augmented realitycapable of significantly reducing the volume and weight thereof andsimplifying the manufacturing process thereof by projecting a virtualimage onto the retina through the pupil by using a reflective unithaving a size smaller than that of the pupil of a human and also capableof always providing a clear virtual image regardless of whether or not auser changes a focal distance.

FIG. 3 is a diagram showing an optical device 100 for augmented realitysuch as that disclosed in patent document 1.

The optical device 100 for augmented reality shown in FIG. 3 includes animage output unit 10, a reflective unit 20, and an optical means 30.

The image output unit 10 is a means for outputting augmented realityimage light corresponding to an image for augmented reality, and may beimplemented as, for example, a small-sized display device.

The reflective unit 20 provides an image for augmented reality to a userby reflecting augmented reality image light, output from the imageoutput unit 10, to the pupil of the user. The reflective unit 20 isembedded and disposed inside the optical means 30 at an appropriateangle between the image output unit 10 and the pupil so that it canreflect image light corresponding to an image for augmented reality,output from the image output unit 10, to the pupil.

The optical means 30 is a means for transmitting at least part of realobject image light, which is image light output from a real object(anobject of real world), and may be, for example, a lens of eyeglasses.The reflective unit 20 is embedded inside the optical means 30.

A frame unit 40 is a means for fastening and supporting both the imageoutput unit 10 and the optical means 30, and may be constructed, forexample, in the form of eyeglasses.

The reflective unit 20 shown in FIG. 3 is formed to have a size smallerthan that of the average of pupil of humans, i.e., 8 mm or less. Byforming the reflection unit 20 smaller than the average pupil of humansas described above, the depth of field for light entering the pupilthrough the reflection unit 20 may be made almost infinite, i.e.,considerably deep.

In this case, the depth of field refers to a range within which an imagefor augmented reality is recognized as being in focus. When the depth offield increases, this means that a focal distance for an image foraugmented reality increases. Accordingly, even when a user changes thefocal distance for the real world while gazing at the real world, animage for augmented reality is always recognized as being in focusregardless of such a change. This may be a kind of pinhole effect.

Accordingly, the optical device 100 for augmented reality shown in FIG.3 may always provide a clear virtual image for an image for augmentedreality even when a user changes the focal distance while gazing at areal object in the real world.

The present invention is characterized by providing an optical devicefor augmented reality based on the technology described in patentdocument 1. Optical devices 200 to 1300 for augmented reality havingimproved light efficiency according to the present invention will bedescribed in detail below with reference to FIGS. 4 to 34 .

First Embodiment

FIG. 4 is a diagram showing an optical device 200 for augmented realityhaving improved light efficiency according to a first embodiment of thepresent invention.

Referring to FIG. 4 , the optical device 200 for augmented realityhaving improved light efficiency (hereinafter simply referred to as the“optical device 200 for augmented reality”) includes a reflective means20 and an optical means 30.

The image output unit 10 is a means for outputting augmented realityimage light, which is image light corresponding to an image foraugmented reality, toward the optical means 30. For example, the imageoutput unit 10 may include: a display device 11, such as a small-sizedLCD, configured to output augmented reality image light through a screenby displaying an image for augmented reality on the screen; and acollimator 12 configured to output light obtained by collimating theaugmented reality image light output from the display device 11.

The collimator 12 is not essential, and may be omitted. Furthermore,there may be used other various optical elements that are each composedof a combination of the collimator 12, and at least any one of areflective means, a refractive means and a diffractive means thatreflect, refract or diffract augmented reality image light output fromthe display device 11 and transfer the light toward the optical means30.

Since the image output unit 10 itself is not a direct target of thepresent invention and has been known in the prior art, a detaileddescription thereof will be omitted below.

Meanwhile, the image for augmented reality refers to a virtual imagethat is displayed on the screen of the display device 11 of the imageoutput unit 10 and transferred to the pupil 40 of a user through thereflective means 20 and the optical means 30. The image for augmentedreality may be a still image or moving image in the form of an image.

Such an image for augmented reality is output from the image output unit10 as augmented reality image light corresponding to the image foraugmented reality, and is transferred to the pupil 40 of a user throughthe reflective means 20 and the optical means 30, thereby providing avirtual image to the user. At the same time, user receives real objectimage light, which is image light output from a real object present inthe real world, directly through the eye via the optical means 30, sothat an augmented reality service can be provided to the user.

In the embodiment of FIG. 4 , there is shown a configuration in whichtotal reflection occurs once on an inner surface of the optical means30. Accordingly, the image output unit 10 is disposed at a positionshown in FIG. 4 , but this is an example. When a total reflectionstructure is not employed or when total reflection is employed twice ormore, the image output unit 10 is disposed accordingly at a positionappropriate to transfer augmented reality image light to the reflectivemeans 20 through the optical means 30. In any case, the image outputunit 10 may be disposed at an appropriate position by taking intoconsideration the position and angle of the reflective means 20 and theposition of the pupil 40 to be described later.

The reflective means 20 is a means for transferring augmented realityimage light, corresponding to an image for augmented reality output fromthe image output unit 10, to the pupil 40 of the eye of a user byreflecting the augmented reality image light toward the pupil 40,thereby providing the image for augmented reality, which is a virtualimage, to the user.

In FIG. 4 , the reflective means 20 includes a plurality of reflectiveunits 21 to 29, and reference symbol 20 designates the entirety of theplurality of reflective units 21 to 29.

The reflective means 20 is embedded and disposed inside the opticalmeans 30, as shown in FIG. 4 .

As will be described later, the optical means 30 includes a firstsurface 31 through which the augmented reality image light reflectedfrom the reflective means 20 and at least part of real object imagelight go toward the pupil 40 of the user, and a second surface 32 beingopposite to the first surface 31 and into which the real object imagelight enters. The reflective means 20 is embedded and disposed in aninternal space between the first and second surfaces 31 and 32 of theoptical means 30.

The first surface 31 of the optical means 30 is a surface facing thepupil 40 of the user when the user places the optical device 200 foraugmented reality in front of the pupil 40, and the second surface 32thereof is the opposite surface, i.e., a surface facing an object in thereal world. The reflective means 20 is disposed in an internal spacebetween the first and second surfaces 31 and 32 of the optical means 30.

Meanwhile, although the augmented reality image light output from theimage output unit 10 is illustrated as being totally reflected from theinner surface of the optical means 30 once and then transferred to thereflective means 20 in the embodiment of FIG. 4 , this is an example.

The augmented reality image light output from the image output unit 10may be directly transferred to the reflective means 20 through the innerspace of the optical means 30 without employing total reflection, or maybe totally reflected by the inner surface of the optical means 30 atleast twice and then transferred to the reflective means 20.

In the case where augmented reality image light is totally reflected bythe inner surface of the optical means 30 at least twice and the numberof total reflections is an even number (2n, where n is a naturalnumber), the augmented reality image light output from the image outputunit 10 enters the first surface 31 firstly rather than the secondsurface 32 of the optical means 30 as shown in FIG. 4 , is totallyreflected 2n times between the second surface 32 and the first surface31, and is then transferred to the reflective means 20. Accordingly, inthis case, the augmented reality image light output from the imageoutput unit 10 is output toward the first surface 31, unlike in FIG. 4 .

In the case where augmented reality image light is totally reflected atthe inner surface of the optical means 30 at least twice and the numberof total reflections is an odd number (2n−1, where n is a naturalnumber), the augmented reality image light output from the image outputunit 10 enters the second surface 32 of the optical means 30 like inFIG. 4 , is totally reflected 2n−1 times between the first surface 31and the second surface 32, and is then transferred to the reflectivemeans 20.

In the case of configurations employing total reflection, in any case,the augmented reality image light entering the reflective means 20 comesfrom the second surface 32 of the optical means 30.

In the embodiment of FIG. 4 , the reflective means 20 includes aplurality of reflective units 21 to 29, and the reflective units 21 to29 are appropriately disposed inside the optical means 30 by taking intoconsideration the locations of the image output unit 10 and the pupil 40in order to transfer the augmented reality image light transferred tothe reflective units 21 to 29 to the pupil 40 of the user by reflectingthe augmented reality image light.

As shown in FIG. 4 , in the case where there is employed a configurationin which the augmented reality image light output from the image outputunit 10 is totally reflected by the second surface 32 of the opticalmeans 30 and then transferred to the reflective units 21 to 29, theinclination angles of the reflective units 21 to 29 are accordingly setby taking into consideration the location the augmented reality imagelight entering the second surface 32 of the optical means 30 from theimage output unit 10, the augmented reality image light totallyreflected by the second surface 32 and output to the reflective units 21to 29, and the pupil 40.

Meanwhile, each of the reflective units 21 to 29 is preferably formed tohave a size smaller than that of the pupil of a human, i.e., 8 mm orless, more preferably 4 mm or less, so that a pinhole effect may beachieved by increasing the depth of field, as described with referenceto FIG. 3 above.

In other words, each of the reflective units 21 to 29 is preferablyformed to have a size smaller than that of the average pupil of humans,i.e., 8 mm or less, more preferably 4 mm or less. By this, the depth offield for the light entering the pupil through each of the reflectiveunits 21 to 29 may be made almost definite, i.e., considerably deep.Accordingly, a pinhole effect that allows an image for augmented realityto be recognized as being in focus at any time may be achieved,regardless of a change of the focal distance which may happen when auser changes the focal distance for the real world while gazing at thereal world and.

In this case, the size of each of the reflective units 21 to 29 isdefined to mean the maximum length between any two points on the edgeboundary of each of the reflective units 21 to 29.

Furthermore, the size of each of the reflective units 21 to 29 may bethe maximum length between any two points on the edge boundary of anorthogonal projection obtained by projecting each of the reflectiveunits 21 to 29 onto a plane that is perpendicular to straight linesbetween the pupil 40 and the reflective units 21 to 29 and includes thecenter of the pupil 40.

Meanwhile, when the reflective units 21 to 29 are 2 or more in number,as shown in FIG. 4 , each of the reflective units 21 to 29 needs to bearranged so as not to prevent the augmented reality image light totallyreflected by the second surface 32 of the optical means 30 from beingtransferred to other reflective units 21 to 29.

For this purpose, in the present embodiment, at least two reflectiveunits 25 to 29 of the plurality of reflective units 21 to 29 arearranged closer to the second surface 32 of the optical means 30 as thedistance from the image output unit 10 increases. In other words, thismeans that at least two reflective units 25 to 29 of the plurality ofreflective units 21 to 29 are arranged father from the first surface 31of the optical means 30, i.e., the pupil 40, as the distance from theimage output unit 10 increases.

In this case, there may be a case where the second surface 32 of theoptical means 30 is formed as a curved surface or is disposed at aninclination angle with respect to the pupil 40. Accordingly, the factthat at least two reflective units 25 to 29 of the plurality ofreflective units 21 to 29 are arranged closer to the second surface 32of the optical means 30 as the distance from the image output unit 10increases means that there are at least two reflective units 25 to 29 ofthe reflective units 21 to 29 that are closer to a plane perpendicularto a straight line in a forward direction from the pupil 40 andincluding a point at which the straight line meets the second surface 32of the optical means 30 as the distance from the image output unit 10increases.

FIG. 5 is a diagram illustrating a structure in which reflective units21 to 29 are arranged.

Referring to FIG. 5 , the reflective units 21 to 29 are embedded andarranged between the first and second surfaces 31 and 32 of an opticalmeans 30. When the optical means 30 is viewed from the side, thereflective units 21 to 24 have the same distance to the second surface32 of the optical means 30, whereas the reflective units 25 to 29 arearranged closer to the second surface 32 of the optical means 30 as thedistance from the image output unit 10 increases.

In FIG. 5 , when the optical means 30 is viewed from the side, thereflective units 21 to 24 are arranged such that a virtual lineconnecting the centers of the reflecting units 21 to 24 forms a straightline parallel to the second surface 32 and the reflective units 25 to 29are arranged such that a virtual line connecting the centers of thereflecting units 25 to 29 forms a curved line. In other words, thereflective units 21 to 24 are arranged along a straight line, and thereflective units 25 to 29 are arranged along a curved line.

Although the four reflective units 21 to 24 are illustrated as beingarranged along a straight line and the five reflective units 25 to 29are illustrated as being arranged along a curved line in FIG. 5 , thisis an example. It is obvious that the number of reflective unitsarranged along each of the straight and curved lines may be changedaccording to their example of use. Alternatively, all reflective units21 to 29 may be arranged along a curved line.

In this case, the straight and curved lines are shapes in atwo-dimensional (2D) plane when viewed from the side of the opticalmeans 30. However, when the image output unit 10 is located on the sideof the pupil 40 rather than being located above the pupil 40 as shown inFIG. 4 , the reflective units 21 to 29 may be arranged along a straightor curved line in a 2D plane when viewed from a position above or belowthe optical means 30.

FIG. 6 is a perspective view of the optical device 200 for augmentedreality, which is illustrated in FIGS. 4 and 5 .

Referring to FIG. 6 , when the optical device 200 for augmented realityis placed in front of the pupil 40 of a user, let's assume that aforward direction from the pupil 40 is referred to as an x axis, any oneof line segments being parallel to a vertical line between the imageoutput unit 10 and the x axis along the x axis and passing between thefirst and second surfaces 31 and 32 of the optical means 30 is referredto as an y axis, and a line segment perpendicular to both the x axis andthe y axis is referred to as an z axis. Then, the reflective units 21 to29 are seen as shown in FIG. 5 when the optical device 200 for augmentedreality is viewed toward a plane perpendicular to the z axis.

In other words, when the optical means 30 is viewed toward a planeperpendicular to the z axis from outside, at least two reflective units25 to 29 among the plurality of reflective units 21 to 29 are arrangedcloser to the second surface 32 of the optical means 30 in an internalspace between the first and second surfaces 31 and 32 of the opticalmeans 30 as the distance from the image output unit 10 increases.

In this case, the plurality of reflective units 21 to 29 may be arrangedin a plane perpendicular to the z axis in spaces between the first andsecond surfaces 31 and 32 of the optical means 30.

Meanwhile, as shown in FIGS. 5 and 6 , it can be seen that thereflective units 21 to 24 are arranged closer to the first surface 31 ofthe optical means 30.

In this case, the second surface 32 is a surface that is entered by realobject image light, as described above. This surface is a surface fromwhich augmented reality image light is finally totally reflectedimmediately before entering the reflective units 21 to 29 when a totalreflection structure is employed.

Meanwhile, it can be seen that the reflective units 25 to 29 arearranged in a curved shape so as to be closer to the second surface 32of the optical means 30 in a direction toward the bottom one of thereflective units 25 to 29. In other words, the reflective units 25 to 29are arranged closer to the second surface 32 as the distance from theimage output unit 10 increases.

FIG. 7 shows diagrams illustrating the effects of structures in whichreflective units 21 to 29 are arranged.

FIG. 7(a) shows a case where the reflective units 21 to 29 are arrangedin a structure such as that shown in FIGS. 4 to 6 , i.e., a structure inwhich at least two of the reflective units 25 to 29 are arranged closerto the second surface 32 as the distance from the image output unit 10increases, and FIG. 7(b) shows a case where all the reflective units 21to 29 are arranged in a straight line, i.e., all the reflective units 21to 29 are arranged to have the same distance to the second surface 32regardless of the distance from the image output unit 10.

Referring to FIG. 7(b), all the reflective units 21 to 29 are arrangedalong a straight line in a direction perpendicular to a forwarddirection from the pupil 40 (in other words, all the reflective units 21to 29 are arranged to have the same distance to the second surface 32 ofthe optical means 30 regardless of the distance from the image outputunit 10). In this case, it can be seen that the augmented reality imagelight totally reflected from the second surface 32 of the optical means30 does not appropriately reach the lower reflective units 28 and 29.

In contrast, referring to FIG. 7(a), the reflective units 25 to 29 arearranged closer to the second surface 32 of the optical means 30 as thedistance from the image output unit 10 increases. Accordingly, in thiscase, it can be seen that the augmented reality image light totallyreflected from the second surface 32 of the optical means 30 istransferred to all the lower reflective units 28 and 29.

Meanwhile, the reflective units 21 to 29 are arranged to be inclined atan appropriate inclination angle in order to transfer the augmentedreality image light, transferred to the reflective units 21 to 29, tothe pupil 40 of user by reflecting the augmented reality image light, asdescribed above. Each of the reflective units 21 to 29 is arranged tohave an inclination angle of at least 45 degrees or less with respect toa forward direction from the center of the pupil 40 of the user.

FIGS. 8 and 9 are diagrams illustrating the inclination angles ofreflective units.

In FIG. 8 , only one reflective unit 21 is shown for ease ofdescription. Referring to FIG. 8 , the reflective unit 21 is arranged tobe inclined at an inclination angle e with respect to a forwarddirection from the center of the pupil 40 of the user. This inclinationangle is preferably 45 degrees or less. The reason for this is that whenthe inclination angle e of the reflecting unit 21 exceeds 45 degrees,the augmented reality image light entering the reflective unit 21 maynot be appropriately transferred toward the pupil 40.

FIG. 9(a) shows a case where the inclination angle e of the reflector 20is 45 degrees or less, and FIG. 9(b) shows a case where the inclinationangle e of the reflector 20 exceeds 45 degrees.

Referring to FIG. 9(a), the inclination angle 0 of the reflective unit20 is formed to be 45 degrees or less. In this case, it can be seen thatthe augmented reality image light totally reflected from the secondsurface 32 (the input surface) of the optical means 30 converges to thepupil 40 through the reflective unit 20.

In FIG. 9 (a), the dotted lines marked outside the second surface 32 ofthe optical means 30 are shown by extending the rays of augmentedreality image light, totally reflected from the second surface 32 of theoptical means 30 and entering the reflective units 20, out of the secondsurface 32 of the optical means 30. It can be seen that these dottedlines meet at a point outside the second surface 32 of the optical means30. This means that the rays of augmented reality image lighttransmitted to the pupil 40 through the reflective units 20 converge tothe pupil 40.

Meanwhile, as shown in FIG. 9(b), it can be seen that when theinclination angle θ of the reflective units 20 exceeds 45 degrees, imagelight diverges through the reflective units 20 without converging if itis assumed that the image light is output from the pupil 40.Accordingly, when a case where augmented reality image light is outputfrom the image output unit 10 is taken into consideration, it means thatthe optical paths of the augmented reality image light cannot convergeto the pupil 40 and thus may not have an input surface at the sameposition. Finally, this means that the augmented reality image lightoutput from the image output unit 10 may not be appropriatelytransferred to the pupil 40 through the reflective units 20 after beingtotally reflected from the inner surface of the optical means 30.

Although FIG. 9 illustrates the case where augmented reality image lightis totally reflected from the second surface 32 of the optical means 30once, the same is true when total reflection is not employed or totalreflection is employed twice or more. When total reflection is notemployed, the image output unit 10 is located on second surface-sideextension lines of lines, connecting the second surface 32 of theoptical means 30 and the reflective units 20. Likewise, in this case,the reflective units 20 have an angle of at least 45 degrees or lesswith respect to a forward direction from the center of the pupil 40 ofthe user.

Meanwhile, the optical means 30 is a means that has reflective units 21to 29 embedded and arranged therein and transmits at least part of realobject image light, which is image light output from a real object,therethrough toward the pupil 40 of the eye of a user.

In this case, the fact that at least part of real object image light istransmitted toward the pupil 40 means that the light transmittance ofreal object image light does not necessarily have to be 100%.

Furthermore, as described above, the optical means 30 directly transfersthe augmented reality image light, output from the image output unit 10,to the reflective units 21 to 29 through the inside of the optical means30, or transfers the augmented reality image light, output from theimage output unit 10, to the reflective units 21 to 29 after totallyreflecting the augmented reality image light on the inner surface of theoptical means 30 at least once.

As described above, the optical means 30 includes the first surface 31through which the augmented reality image light reflected from thereflective units 21 to 29 and at least part of real object image lightgo toward the pupil 40 of a user, and the second surface 32 beingopposite to the first surface 31 and to be entered by real object imagelight. The reflective units 21 to 29 are embedded and arranged in aninternal space between the first and second surfaces 31 and 32 of theoptical means 30.

The optical means 30 may be composed of a lens made of glass material,plastic material, or other synthetic resin materials, and may havevarious refractive indices and transparency.

Although the first and second surfaces 31 and 32 of the optical means 30are shown as being parallel to each other, this is an example, and theymay be configured not to be parallel to each other.

Furthermore, at least any one of the first and second surfaces 31 and 32of the optical means 30 may be formed as a curved surface. In otherwords, any one of the first and second surfaces 31 and 32 may be formedas a curved surface, and both the first and second surfaces 31 and 32may be formed as curved surfaces.

In this case, the curved surface may be a concave surface or a convexsurface. The concave surface means that when a corresponding surface isviewed from the front, the central portion thereof is formed thinnerthan the edge portion thereof and become concave. The convex surfacemeans that when a corresponding surface is viewed from the front, thecentral portion is formed thicker than the edge portion thereof andprotrudes convexly.

FIGS. 10 and 11 are diagrams illustrating the overall operation of theoptical device 200 for augmented reality according to the embodimentdescribed with reference to FIGS. 4 to 9 , and are directed to a casewhere there is employed a total reflection structure such as that shownin FIG. 4 .

In FIG. 10 , only five reflective units 21 to 25 are shown for ease ofdescription.

Referring to FIGS. 10(a), 10(b), and 10(c), it can be seen that rays ofaugmented reality image light entering at different angles are totallyreflected from the second surface 32 of the optical means 30 and aretransferred to an eye box by the reflective units 21 to 25 having theabove-described inclination angle and arrangement structure.

The reflective units 21 to 23 are being used in FIG. 10(a), thereflective units 22 to 24 are being used in FIG. 10(b), and thereflective units 23 to 25 are being used in FIG. 10(c). It can be seenthat these reflective units transfer augmented reality image light to aneye box at an angle corresponding to the incident angle of the lightpath of the augmented reality image light, i.e., the exit angle of thelight path of the augmented reality image light output from the imageoutput unit 10.

In this case, the eye box is the maximum space in which the pupil 40 ofthe user can be located in viewing augmented reality image light as itis output from the image output unit 10. The second surface 32 of theoptical means 30 acts as an input surface, and the augmented realityimage light totally reflected from the input surface is all output inthe direction of the eye box through the reflective units 21 to 25.

Meanwhile, FIG. 11 shows the rays of augmented reality image light shownin FIGS. 10(a), 10(b), and 10(c) together. Referring to FIG. 11 , it canbe seen that the augmented reality image light output from the imageoutput unit 10 enters through the upper portion of the optical means 30acting as an input pupil, is totally reflected through the secondsurface 32 of the optical means 30, is reflected through the reflectiveunits 20, and is then transferred to the eye box through the firstsurface 31 of the optical means 30 acting as an exit pupil. In thiscase, the distance between the eye box where the pupil 40 can be locatedand the optical means 30 becomes an eye relief.

As shown in FIGS. 10 and 11 , it can be seen that the augmented realityimage light output from the image output unit 10 and totally reflectedfrom the input surface of the optical means 30 is all transferred towardthe eye box by the inclination angle and arrangement structures of thereflective units 20 such as those described above, and thus the lightefficiency of augmented reality image light may be considerablyimproved.

FIG. 12 is a diagram showing the configuration of an optical device 300for augmented reality according to a modification of the firstembodiment of the present invention.

The optical device 300 for augmented reality according to the embodimentshown in FIG. 12 has the same basic configuration as the optical device200 for augmented reality according to the embodiment described withreference to FIGS. 4 to 11 , however, the optical device 300 ischaracterized in that a plurality of reflective means 20 are formed andeach of the reflective means 20 includes a plurality of reflective units21 to 29.

In this case, a plurality of reflective means 20 are arranged asfollows. As described above, when the optical device 300 for augmentedreality is placed in front of the pupil 40 of a user, let's assume thata forward direction from the pupil 40 is referred to as an x axis, anyone of line segments being parallel to a vertical line between an imageoutput unit 10 and the x axis along the x axis and passing between thefirst and second surfaces 31 and 32 of an optical means 30 is referredto as an y axis, and a line segment perpendicular to both the x axis andthe y axis is referred to as an z axis. Then, each reflective means 20of the plurality may be arranged at intervals in parallel with eachother along the z-axis direction.

In this case, each of the reflective means 20 may be arranged such thateach of reflective units 21 to 29 constituting each of the reflectivemeans 20 can be located along a virtual straight line parallel to the zaxis along with any one of reflective units 21 to 29 included inadjacent the reflective means 20. Accordingly, when viewed toward aplane perpendicular to the z axis from outside, a plurality ofreflective means 20 are seen the same as shown in FIG. 5 .

According to the embodiment of FIG. 12 , wider field of view and an eyebox in the z-axis direction can be provided with the effects as abovedescribed with reference to FIGS. 4 to 11 .

FIG. 13 is a diagram showing the configuration of an optical device 400for augmented reality according to another modification of the firstembodiment of the present invention.

The optical device for augmented reality 400 according to the embodimentshown in FIG. 13 is characterized in that a plurality of reflectivemeans 20 are formed, as in the optical device 300 for augmented realityaccording to the embodiment illustrated in FIG. 12 , and a plurality ofthe reflective means 20 are arranged such that each of the reflectiveunits 21 to 29 included in each of the reflective means 20 can beprevented from being located along a virtual straight line parallel tothe z axis along with any one of reflective units 21 to 29 included inadjacent reflective means 20.

As shown in FIG. 13 , when the reflective units 21 to 29 of a firstreflective means 20 from the right side of the z axis are compared withthe reflective units 21 to 29 of a second reflective means 20 adjacentto the first reflective means 20 sequentially from the upper side (aside near the image output unit 10) of the y-axis direction, it can beseen that the first and second reflective means 20 are arranged suchthat each of the reflective units 21 to 29 of the first reflective means20 can be prevented from being located along a virtual straight lineparallel to the z axis along with any one of the reflective units 21 to29 of the second reflective means 20. In other words, it can be seenthat when viewed in the z-axis direction, the reflective units 21 to 29of the first reflective means 20 and the reflective units 21 to 29 ofthe second reflective means 20 are not aligned with each other alongstraight lines parallel to the z axis, but are arranged alternately inthe y-axis direction.

FIG. 14 is a diagram showing the configuration of an optical device 500for augmented reality according to still another modification of thefirst embodiment of the present invention.

The optical device 500 for augmented reality according to the embodimentshown in FIG. 14 is characterized in that it has the same basicconfiguration as the optical device 200 for augmented reality accordingto the embodiment described with reference to FIGS. 4 to 11 but each ofthe reflective units 21 to 29 is formed in bar shapes extending in thez-axis direction.

In other words, as described above, when the optical device 500 foraugmented reality is placed in front of the pupil 40 of a user, let'sassume that a forward direction from the pupil 40 is referred to as an xaxis, any one of line segments being parallel to a vertical line betweenan image output unit 10 and the x axis along the x axis and passingbetween the first and second surfaces 31 and 32 of an optical means 30is referred to as an y axis, and a line segment perpendicular to boththe x axis and the y axis is referred to as an z axis. Then, each of theplurality of reflective units 21 to 29 is formed in bar shapes extendingin the z-axis direction.

In this case, when viewed toward a plane perpendicular to the z-axisfrom outside, the size of each of the reflective units 21 to 29 ispreferably formed to be 4 mm or less. Also, even in this embodiment,when the optical means 30 is viewed toward a plane perpendicular to thez axis from outside, the shapes of the reflective units 21 to 29 areseen the same as shown in FIG. 5 .

Meanwhile, in the embodiment, at least some of the reflective units 21to 29 may have a different size(s). Even in this case, the size of eachof the reflective units 21 to 29 is preferably formed to be 4 mm orless, as described above.

Furthermore, it is preferable that individual reflective units 21 to 29are arranged at the same intervals. However, at least some of thereflective units 21 to 29 may be arranged in intervals different fromthose at which the other reflective units are arranged.

Furthermore, at least some of the reflective units 21 to 29 may becomposed of half mirrors that partially reflect light.

Furthermore, at least some of the reflective units 21 to 29 may becomposed of refractive elements or diffractive elements other thanreflective means.

Furthermore, at least some of the reflective units 21 to 29 may becomposed of optical elements such as notch filters that selectivelytransmit light therethrough according to its wavelength.

Furthermore, at least some of the reflective units 21 to 29 may have asurface coated with a material that absorbs light without reflectinglight, wherein the coated surface is opposite surface to a surfacereflecting the augmented reality image light.

Moreover, at least some of the reflective units 21 to 29 may have curvedsurfaces. In this case, the curved surfaces may be concave surfaces orconvex surfaces.

FIG. 15 is a diagram illustrating a state in which the surfaces ofreflective units 21 to 29 are formed as curved surfaces, which showsonly one reflective unit 21 for ease of description.

As shown in FIG. 15 , the surface of the reflective unit 21 is formed asa curved surface, in which the curved surface may be formed as a convexsurface that is convex toward the first surface 31 of the optical means30.

Although the reflective unit 21 having a convex surface convex towardthe first surface 31 is shown in FIG. 15 , this is an example.Alternatively, the reflective unit 21 may be formed to have a concavesurface concave toward the first surface 31.

FIG. 16 is a diagram showing another example of the shape of curvedsurface of the reflecting units 21 to 29, which shows only onereflecting unit 21 for ease of description.

The reflective unit 21 shown in FIG. 16 has a curved surface and whenthe reflective unit 21 is placed in front of the pupil 40 of a user,assuming that a forward direction from the pupil 40 is referred to as anx axis, any one of line segments being parallel to a vertical linebetween an image output unit 10 and the x axis along the x axis andpassing between the first and second surfaces 31 and 32 of an opticalmeans 30 is referred to as an y axis, and a line segment perpendicularto both the x axis and the y axis is referred to as an z axis, then thelength of the reflective unit 21 in the z-axis direction is longer thanthat of the reflective unit 21 in the x-axis direction.

In other words, the reflective unit 21 shown in FIG. 16 is characterizedin that it extends in a bar shape along the z-axis direction inside theoptical means 30 and is formed in a shape obtained by cutting ancylindrical reflective unit in the longitudinal direction thereof.

In FIG. 16 , the reflective unit 21 has a length in the z-axis directionlonger than that in the x-axis direction and is formed as a convexsurface that is convex toward the first surface 31 of the optical means30.

In FIG. 16 , although the reflective unit 21 has a bar shape extendingalong with the z-axis direction, the reflective unit 21 may have a barshape extending along with the y-axis direction, i.e., a bar shape inwhich the length thereof in the y-axis direction is longer than that inthe z-axis direction.

Furthermore, since the reflective unit 21 shown in FIG. 16 is formed ina shape obtained by cutting an overall cylindrical shape in thelongitudinal direction thereof, it has a rectangular shape when thereflecting part 21 is viewed in the y-axis direction, but this is anexample. The reflective unit 21 may be formed to have another shape,such as a circular, triangular, or rectangular shape, as a whole whenviewed in the y-axis direction. In addition, the reflective unit 21 maybe formed in an elliptical shape having a long axis in the x-axisdirection when viewed in the y-axis direction.

Furthermore, although the reflective unit 21 having a convex surfacethat is convex toward the first surface 31 of the optical means 30 isshown in FIG. 16 , this is an example. It is obvious that the reflectiveunit 21 may be formed to have a concave surface that is concave towardthe first surface 31.

Furthermore, the reflective unit 20 described in the embodiment of FIG.14 may be formed in a shape as shown in FIG. 16 . In this case, thereflective unit 20 of FIG. 14 extends entirely along the z-axisdirection inside the optical means 30 and is formed in a single bar. Incontrast, the reflective unit 21 of FIG. 16 may be viewed as beingformed by dividing the bar shape of FIG. 14 .

Second Embodiment

Next, optical devices 600 to 1300 for augmented reality according to asecond embodiment of the present invention will be described withreference to FIGS. 17 to 34 .

FIG. 17 is a diagram showing an optical device 600 for augmented realityaccording to a second embodiment of the present invention.

The optical device 600 for augmented reality according to the secondembodiment shown in FIG. 17 has the same basic configuration as thefirst embodiment shown in FIG. 4 , and is different from the firstembodiment only in the arrangement structure of reflective units 21 to29 constituting a reflective means 20.

The reflective means 20 of the optical device 600 for augmented realityaccording to the second embodiment shown in FIG. 17 includes a firstreflective unit group 20A comprising a plurality of reflective units 21to 24 and a second reflective unit group 20B comprising a plurality ofreflective units 25 to 29, and the reflective means 20 is embedded anddisposed inside the optical means 30 so that the distance between thesecond reflective unit group 20B and an image output unit 10 is largerthan the distance between the first reflective unit group 20A and theimage output unit 10.

In this case, the reflective units 21 to 24 included in the firstreflective unit group 20A are embedded and disposed inside the opticalmeans 30 so that the reflective units 21 to 24 are arranged closer tothe first surface 31 of the optical means 30 as the distance from theimage output unit 10 increases, and the reflective units 25 to 29included in the second reflective unit group 20B are embedded anddisposed inside the optical means 30 so that the reflective units 25 to29 are arranged farther from the first surface 31 of the optical means30 as the distance from the image output unit 10 increases.

There may be a case where at least any one of the first and secondsurfaces 31 and second surface 32 of the optical means 30 is formed as acurved surface, or is not parallel to a plane perpendicular to astraight line in a forward direction from the center of the pupil 40 andis formed to have an inclination angle. Accordingly, being arrangedcloser to the first surface 31 of the optical means 30 as the distancefrom the image output unit 10 increases means being arranged closer to aperpendicular plane present between the first surface 31 and the pupil40 and perpendicular to a straight line in a forward direction from thepupil 40 as the distance from the image output unit 10 increases.

In the same manner, being arranged farther from the first surface 31 ofthe optical means 30 as the distance from the image output unit 10increases means being arranged farther from a perpendicular planepresent between the first surface 31 and the pupil 40 and perpendicularto a straight line in a forward direction from the pupil 40 as thedistance from the image output unit 10 increases.

Since other configurations are the same as those of the first embodimentdescribed above, detailed descriptions thereof will be omitted.

FIG. 18 is a diagram illustrating the arrangement structure of thereflective units 21 to 29 illustrated in FIG. 17 .

Referring to FIG. 18 , as described above, the reflective means 20includes the first reflective unit group 20A and the second reflectiveunit group 20B. The first reflective unit group 20A comprises aplurality of reflective units 21 to 24, and the second reflective unitgroup 20B includes a plurality of reflective units 25 to 29.

It can be seen that the plurality of reflective units 21 to 24constituting the first reflective unit group 20A and the plurality ofreflective units 25 to 29 constituting the second reflective unit group20B are embedded and arranged in an internal space between the first andsecond surfaces 31 and 32 of the optical means 30 and the reflectiveunits 21 to 29 are arranged such that a smooth “C”-shaped curve can beformed when the centers of the reflective units 21 to 29 are connectedwith a virtual line.

Although the reflective units 21 to 24 constituting the first reflectiveunit group 20A are shown as successive reflective units in FIGS. 17 and18 , this is an example. For example, three reflective units 21, 25 and27 that are not adjacent to each other may constitute the firstreflective unit group 20A. This is also true in the case of the secondreflective unit group 20B.

Furthermore, it is obvious that a plurality of the first reflective unitgroup 20A and a plurality of the second reflective unit group 20B may beformed.

Furthermore, not all of the plurality of reflective units 21 to 29constituting the reflective means 20 must be included in any one of thefirst and second reflective unit groups 20A and 20B. It is obvious thatonly some of the plurality of reflective units 21 to 29 constituting thereflective means 20 may constitute the first and second reflective unitgroups 20A and 20B.

FIG. 19 is a perspective view of the optical device 600 for augmentedreality illustrated in FIGS. 17 and 18 .

Referring to FIG. 19 , when the optical device 600 for augmented realityis placed in front of the pupil 40 of a user, let's assume that aforward direction from the pupil 40 is referred to as an x axis, any oneof line segments being parallel to a vertical line from the image outputunit 10 to the x axis along the x axis and passing between the first andsecond surfaces 31 and 32 of the optical means 30 is referred to as an yaxis, and a line segment perpendicular to both the x axis and the y axisis referred to as an z axis. Then, the z axis becomes a line segmentthat passes between the first and second surfaces 31 and 32 of theoptical means 30 and the reflective units 21 to 29 are seen the same asshown in FIGS. 17 and 18 when the optical means 30 or optical device 600for augmented reality is viewed toward a plane perpendicular to the zaxis from outside.

In other words, when the optical means 30 or optical device 600 foraugmented reality is viewed toward a plane perpendicular to the z axis,a plurality of reflective units 21 to 24 constituting the firstreflective unit group 20A are embedded and disposed inside the opticalmeans 30 so that a plurality of reflective units 21 to 24 are arrangedcloser to the first surface 31 of the optical means as the distance fromthe image output unit 10 increases. Also, a plurality of reflectiveunits 25 to 29 constituting the second reflective unit group 20B areembedded and disposed inside the optical means 30 so that a plurality ofreflective units 25 to 29 are arranged farther from the first surface 31of the optical means as the distance from the image output unit 10increases.

Furthermore, the first and second reflective unit groups 20A and 20B arearranged such that the distance between the second reflective unit group20B and the image output unit 10 is longer than the distance between thefirst reflective unit group 20A and the image output unit 10. This meansthat when the optical means 30 is viewed toward a plane perpendicular tothe z axis in FIG. 19 , the first reflective unit group 20A is arrangedabove the second reflective unit group 20B.

FIG. 20 is a diagram illustrating the effect of the arrangementstructure of the reflective units 21 to 29 of the optical device 600 foraugmented reality shown in FIGS. 17 to 19 .

FIG. 20(a) shows a case where the reflective units 21 to 29 have anarrangement structure such as that described in FIGS. 17 to 19 , andFIG. 20(b) shows a case where all the reflective unit 21 to 29 arearranged in a straight line, i.e., a case where all the reflective units21 to 29 are arranged to have the same distance to the first surface 31regardless of the distance from an image output part 10.

Referring to FIG. 20(b), it can be seen that all the reflective units 21to 29 are arranged to have the same distance to the second surface 32 ofthe optical means 30 regardless of the distance from the image outputunit 10, and thus the augmented reality image light totally reflectedfrom the second surface 32 of the optical means 30 does notappropriately reach the lower reflective units 28 and 29.

In contrast, referring to FIG. 20(a), it can be seen that the reflectiveunits 24 and 29 are arranged as described with reference to FIG. 17 toFIG. 19 , and the augmented reality image light totally reflected fromthe second surface 32 of the optical means 30 is transferred to all thereflective units 21 to 29.

Meanwhile, the reflective units 21 to 29 of the second embodimentdescribed with reference to FIGS. 17 to 19 may be arranged to have aninclination angle of 45 degrees or less with respect to a straight linein a forward direction from the center of the pupil 40 of a user, as inthe first embodiment. Since this is the same as previously describedwith reference to FIGS. 8 and 9 , a detailed description thereof will beomitted.

Meanwhile, as described above, the augmented reality image light outputfrom the image output unit 10 may be directly transferred to thereflective units 21 to 29 without being totally reflected inside theoptical unit 30, or may be totally reflected from the inner surface ofthe optical unit 30 at least once and then transferred to the reflectiveunits 21 to 29.

FIGS. 21 to 23 are diagrams illustrating the numbers of times thataugmented reality image light is totally reflected by an optical means30, which show only three reflective units 21 to 23 for ease ofdescription.

FIG. 21 shows a case where augmented reality image light is not totallyreflected inside the optical means 30.

As shown in FIG. 21 , the augmented reality image light output from theimage output unit 10 is directly transferred to the reflective units 21to 23 without being totally reflected inside the optical means 30, isreflected from the reflective units 21 to 23, and is then transferred tothe pupil 40.

FIG. 22 shows a case where augmented reality image light is totallyreflected inside the optical means 30 once.

As shown in FIG. 22 , the augmented reality image light output from theimage output unit 10 is totally reflected from the second surface 32 ofthe optical means 30 once, transferred to the reflective units 21 to 23,and then reflected from the reflective units 21 to 23, thereby beingtransferred to the pupil 40. FIG. 22 corresponds to a case in which anoptical means 30 such as that shown in FIG. 21 is bisected with respectto the x-axis direction and a bisector is used as the second surface 32of the optical means 30.

FIG. 23 shows a case where augmented reality image light is totallyreflected inside the optical means 30 twice.

Referring to FIG. 23 , the augmented reality image light output from theimage output unit 10 is totally reflected from the first surface 31 ofthe optical means 30, totally reflected from the second surface 32again, transferred to the reflective units 21 to 23, and then reflectedfrom the reflective units 21 to 23 again, thereby being transferred tothe pupil 40. FIG. 23 corresponds to a case in which the optical means30 such as that shown in FIG. 21 is trisected with respect to the x-axisdirection and a trisector closer to the pupil 40 is used as the secondsurface 32 of the optical means 30.

Although the reflective units 21 to 23 are shown in a form arranged in astraight line when the optical means 30 is viewed toward a planeperpendicular to the z-axis in FIGS. 21 to 23 , this is simply shown forease of description. The same is applied to a case where the reflectiveunits 21 to 23 have an arrangement structure such as that described withreference to FIGS. 17 to 19 .

FIGS. 24 and 25 are diagrams illustrating the overall operation of theoptical device 600 for augmented reality.

FIGS. 24 and 25 show a case where total reflection occurs twice insidethe optical means 30 as an example, in which case only five reflectiveunits 21 to 25 are shown for ease of description.

Referring to FIGS. 24(a), 24(b), and 24(c), it can be seen that rays ofaugmented reality image light entering at different angles are totallyreflected from the first and second surfaces 31 and 32 of the opticalmeans 30 and are then transferred to an eye box by the reflective units21 to 25 having the same inclination angle and arrangement structure asdescribed above.

The reflective units 21 to 23 are used in FIG. 24(a), the reflectiveunits 22 to 24 are used in FIG. 24(b), and the reflective units 23 to 25are used in FIG. 24(c). These reflective units transfer augmentedreality image light to an eye box at an angle corresponding to theincident angle of the light path of the augmented reality image light,i.e., the exit angle of the light path of the augmented reality imagelight output from the image output unit 10. In this case, the eye box isthe maximum space in which the pupil 40 of the user can be located inviewing augmented reality image light as it is output from the imageoutput unit 10. The first and second surfaces 31 and 32 of the opticalmeans 30 act as input surfaces, and the augmented reality image lighttotally reflected from these input surfaces is all output in thedirection of the eye box through the reflective units 21 to 25.

Meanwhile, FIG. 25 shows the rays of augmented reality image light shownin FIGS. 24(a), 13(b), and 13(c) together. Referring to this drawing, itcan be seen that the augmented reality image light output from the imageoutput unit 10 enters through the upper portion of the optical means 30acting as an input pupil, is totally reflected through the first andsecond surface 31 and 32 of the optical means 30 twice, is reflectedthrough the reflective units 21 to 25, and is then transferred to theeye box through the first surface 31 of the optical means 30 acting asan exit pupil. In this case, the distance between the eye box where thepupil 40 can be located and the optical means 30 is an eye relief.

As shown in FIGS. 24 and 25 , the augmented reality image light outputfrom the image output unit 10 and totally reflected from the first andsecond surface 31 and 32 of the optical means 30 is all transferredtoward the eye box by the inclination angle and arrangement structuresof the reflective units 20 such as those described above, and thus thelight efficiency of augmented reality image light may be considerablyimproved.

FIG. 26 is a diagram showing the configuration of an optical device 700for augmented reality according to a modification of the secondembodiment of the present invention.

The optical device 700 for augmented reality according to the embodimentshown in FIG. 26 is characterized in that it has the same basicconfiguration as the optical device 600 for augmented reality accordingto the second embodiment described with reference to FIG. 17 but aplurality of reflective means 20 are formed, wherein each of theplurality of reflective means 20 includes a first reflective unit group20A comprising a plurality of reflective units 21 to 24 and a secondreflective unit group 20B comprising a plurality of reflective units 25to 29.

The plurality of reflective means 20 are arranged as follows. When theoptical device 700 for augmented reality or an optical means 30 isplaced in front of the pupil 40 of a user, let's assume that a forwarddirection from the pupil 40 is referred to as an x axis, any one of linesegments being parallel to a vertical line from an image output unit 10to the x axis along the x axis and passing between the first and secondsurfaces 31 and 32 of the optical means 30 is referred to as an y axis,and a line segment perpendicular to both the x axis and the y axis isreferred to as an z axis. Then, a plurality of reflective means 20 maybe arranged at intervals in parallel with each other along the z-axisdirection.

In this case, the reflective means 20 may be arranged such that each ofreflective units 21 to 29 constituting each of the reflective means 20can be located along a virtual straight line parallel to the z axisalong with any one of reflective units 21 to 29 included in adjacent oneof the reflective means 20. Accordingly, when the optical means 30 isviewed toward a plane perpendicular to the z axis from outside, theplurality of reflective means 20 is seen the same as shown in FIGS. 17and 18 .

According to the embodiment of FIG. 26 , there is provided the advantageof wider angle of field of view and an eye box in the z-axis directionwhile having the effects described with reference to FIGS. 17 to 19 .

FIG. 27 is a diagram showing the configuration of an optical device 800for augmented reality according to another modification of the secondembodiment of the present invention.

The optical device for augmented reality 800 according to the embodimentshown in FIG. 27 is characterized in that a plurality of reflectivemeans 20 are formed, as in the optical device 700 for augmented realityaccording to the embodiment illustrated in FIG. 26 , and the reflectivemeans 20 are arranged such that each of reflective units 21 to 29constituting each of the reflective means 20 can be prevented from beinglocated along a virtual straight line parallel to the z axis along withany one of reflective units 21 to 29 included in adjacent the reflectivemeans 20.

In other words, as shown in FIG. 27 , when the reflective units 21 to 29of a first reflective means 20 from the right side of the z axis arecompared with the reflective units 21 to 29 of a second reflective means20 adjacent to the first reflective means 20 sequentially from the upperside (a side near the image output unit 10) of the y-axis direction, itcan be seen that the first and second reflective means 20 are arrangedsuch that each of the reflective units 21 to 29 of the first reflectivemeans 20 can be prevented from being located along a virtual straightline parallel to the z axis along with any one of the reflective units21 to 29 of the second reflective means 20.

In other words, when viewed in the z-axis direction, the reflectiveunits 21 to 29 of the first reflective means 20 and the reflective units21 to 29 of the second reflective means 20 are not aligned with eachother along straight lines parallel to the z axis, but are arrangedalternately in the y-axis direction.

FIG. 28 is a diagram showing the configuration of an optical device 900for augmented reality according to still another modification of thesecond embodiment of the present invention.

The optical device 900 for augmented reality according to the embodimentshown in FIG. 14 is characterized in that it has the same basicconfiguration as the optical device 600 for augmented reality accordingto the embodiment described with reference to FIGS. 17 and 18 but eachof the plurality of reflective units 21 to 29 is formed in bar shapes.

In this case, the reflective units 21 to 29 have the followingarrangement structure. When the optical device 900 for augmented realityor an optical means 30 is placed in front of the pupil 40 of a user,let's assume that a forward direction from the pupil 40 is referred toas an x axis, any one of line segments being parallel to a vertical linefrom an image output unit 10 to the x axis along the x axis and passingbetween the first and second surfaces 31 and 32 of the optical means 30is referred to as an y axis, and a line segment perpendicular to boththe x axis and the y axis is referred to as an z axis. Then, each of theplurality of reflective units 21 to 29 is formed in bar shapes extendingalong virtual straight lines parallel to the z axis.

Even in this embodiment, when the optical means 30 is viewed toward aplane perpendicular to the z axis, the shapes of the reflective units 21to 29 are seen the same as shown in FIGS. 17 and 18 .

In the case of the present embodiment, when viewed toward a planeperpendicular to the z-axis from outside, the size of each of thereflective units 21 to 29 is preferably formed to be 4 mm or less.

Meanwhile, in the second embodiment and the modifications of the secondembodiment, at least some of the reflective units 21 to 29 may have adifferent size(s). Even in this case, the size of each of the reflectiveunits 21 to 29 is preferably formed to be 4 mm or less, as describedabove.

It is preferable that individual reflective units 21 to 29 are arrangedat the same intervals, however, at least some of the reflective units 21to 29 may be arranged in intervals different from those at which theother reflective units are arranged.

Furthermore, at least some of the reflective units 21 to 29 with respectto the x axis may be inclined at an inclination angle different from theinclined angle at which the other reflective units are inclined.

Furthermore, at least some of the reflective units 21 to 29 may becomposed of half mirrors that partially reflect light.

Furthermore, at least some of the reflective units 21 to 29 may becomposed of refractive elements or diffractive elements other thanreflective means.

Furthermore, at least some of the reflective units 21 to 29 may becomposed of optical elements such as notch filters that selectivelytransmit light therethrough according to its wavelength.

Furthermore, at least some of the reflective units 21 to 29 may have asurface coated with a material that absorbs light without reflectinglight and wherein the coated surface is opposite surface to a surfacereflecting the augmented reality image light.

Moreover, at least some of the reflective units 21 to 29 may have curvedsurfaces. In this case, the curved surfaces may be concave surfaces orconvex surfaces.

In this case, the shape of the reflective units 21 to 29 may be formedaccording to any one of the methods described with reference to FIGS. 15and 16 .

FIGS. 29 to 31 are diagrams showing the configuration of an opticaldevice 1000 for augmented reality according to still anothermodification of the second embodiment of the present invention.

FIG. 29 is a front view showing an optical device 1000 for augmentedreality that is viewed from the pupil 40, FIG. 30 is a side view of theoptical device 1000 for augmented reality that is viewed in the z-axisdirection as described above, and FIG. 31 is a plan view of the opticaldevice 1000 for augmented reality that is viewed in the y-axis directionas described above.

The optical device 1000 for augmented reality shown in FIGS. 29 to 31 isthe same as the optical device for augmented reality 700 shown in FIG.26 in that a plurality of reflective means 20 are formed therein,however, the optical device 1000 is different from the optical device700 shown in FIG. 26 in that there is at least one reflective means 20that has a different distance to the first surface 31 of the opticalmeans 30.

In other words, when the optical device 1000 for augmented reality orthe optical means 30 is placed in front of the pupil 40 of a user,assuming that a forward direction from the pupil 40 is referred to as anx axis, any one of line segments being parallel to a vertical line froman image output unit 10 to the x axis along the x axis and passingbetween the first and second surfaces 31 and 32 of the optical means 30is referred to as an y axis, and a line segment perpendicular to boththe x axis and the y axis is referred to as an z axis, then there is atleast one reflective means 20 that has a different distance to the firstsurface 31 of the optical means 30.

In other words, this means that at least part of the plurality ofreflective means 20 is arranged so as not to be superimposed on theother reflective means 20 when the optical means 30 is viewed toward aplane perpendicular to the z-axis from outside, as shown in FIG. 30 .

In the embodiments of FIGS. 29 to 31 , the reflective means 20 arearranged such that the distance between two reflective means 20indicated by diagonal lines and the first surface 31 of the opticalmeans 30, the distance between two reflective means 20 indicated by ablack color and the first surface 31 of the optical means 30, and thedistance between one reflective means 20 indicated by a white color andthe first surface 31 of the optical means 30 are different from oneanother.

Although the distance between each of the reflective means 20 indicatedby diagonal lines and the first surface 31 of the optical means 30 aresame to each other and the distance between each of the reflective means20 indicated by a black color and the first surface 31 of the opticalmeans 30 are same as to each other, this is an example. It is obviousthat the reflective means 20 may be arranged such that the distancesbetween the reflective means 20 and the first surface 31 of the opticalmeans 30 are all different from one another.

It is obvious that the arrangement structure of the reflective means 20according to the embodiment shown in FIGS. 29 to 31 may be applied tothe first embodiment without change.

FIG. 32 is a diagram showing the configuration of an optical device 1100for augmented reality according to still another modification of thesecond embodiment of the present invention, which illustrates variousconfigurations of an image output unit 10.

In the present invention, the image output unit 10 generally includes adisplay device 11 and a collimator 12, as described above. Thecollimator 12 of the image output unit 10 of the optical device 1100 foraugmented reality shown in FIG. 32 is characterized in that it isimplemented by combining a concave mirror 121 and a beam splitter 122.

As shown in FIG. 32 , the augmented reality image light output from thedisplay device 11 is transferred to the concave mirror 121 by the beamsplitter 122, the augmented reality image light reflected from theconcave mirror 121 enters the second surface 32 of the optical means 30through the beam splitter 122, and then the entering augmented realityimage light is transferred to the pupil 40 through the above-describedprocess.

FIG. 33 is a diagram showing the configuration of an optical device 1200for augmented reality according to still another modification of thesecond embodiment of the present invention.

The optical device for augmented reality 1200 shown in FIG. 33 issimilar to the embodiment shown in FIG. 32 , and is characterized inthat an image output unit 10 is constructed by arranging two concavemirrors 121 to be opposite to each other.

In other words, in the embodiment shown in FIG. 33 , the augmentedreality image light output from a display device 11 is transferred toone concave mirror 121A by a beam splitter 122, reflected from theconcave mirror 121A, passed through the beam splitter 122, transferredto an opposite concave mirror 121B, reflected from the concave mirror121B again, transferred to the second surface 32 of the optical means 30through the beam splitter 122, and finally transferred to the pupil 40through the above-described process.

FIG. 34 is a diagram showing the configuration of an optical device 1300for augmented reality according to still another modification of thesecond embodiment of the present invention.

The embodiment shown in FIG. 34 is similar to the embodiment shown inFIG. 32 , and is different from the embodiment shown in FIG. 32 in thatthe augmented reality image light output from an image output unit 10 istransferred to an optical means 30 via an auxiliary reflective unit 80.

In other words, in the embodiment shown in FIG. 34 , the augmentedreality image light output from a display device 11 is transferred to aconcave mirror 121 by a beam splitter 122, the augmented reality imagelight reflected from the concave mirror 121 passes through the beamsplitter 122, is transferred to the auxiliary reflective unit 80, isreflected from the auxiliary reflective unit 80, and is transferred tothe second surface 32 of the optical means 30, and the transferredaugmented reality image light is finally transferred to the pupil 40through the above-described process.

The embodiments shown in FIGS. 32 to 34 illustrate examples of theconfiguration of the image output unit 10. It is obvious that the imageoutput unit 10 may be constructed in various other forms.

Furthermore, it is obvious that the embodiments shown in FIGS. 32 to 34may be applied to the above-described image output unit 10 of the firstembodiment without change.

While the configuration of the present invention has been described withreference to some embodiments of the present invention, it is obviousthat the present invention is not limited to the above embodiments andvarious modifications and alterations may be made by those skilled inthe art without departing from the scope and spirit of the presentinvention.

For example, in the above embodiments, the optical devices 200 to 1300for augmented reality may be fabricated independently of the imageoutput unit 10, and thus the image output unit 10 has been described asbeing not an essential component for the optical devices 200 to 1300 foraugmented reality. However, as described with reference to FIGS. 32 to34 , an implementation may be made in the form of an integrated moduleincluding the image output unit 10.

According to the present invention, there is provided the optical devicefor augmented reality, which is capable of improving the lightefficiency of the augmented reality image light transferred to an eyebox.

Furthermore, according to the present invention, there is provided theoptical device for augmented reality, in which the reflective means fortransferring the augmented reality image light, output from the imageoutput unit, to the pupil is formed a curved arrangement structure closeto a C shape, so that the light efficiency of the augmented realityimage light transferred to an eye box is improved.

What is claimed is:
 1. An optical device for augmented reality having improved light efficiency, the optical device comprising: a reflective means configured to transfer augmented reality image light, which is image light corresponding to an image for augmented reality output from an image output unit, to a pupil of an eye of a user by reflecting the augmented reality image light toward the pupil, thereby providing the image for augmented reality to the user; and an optical means adapted such that the reflective means is embedded and disposed therein, and configured to transmit at least part of real object image light, which is image light output from a real object, therethrough toward the pupil of the eye of the user; wherein the optical means includes a first surface through which the augmented reality image light reflected from the reflective means and at least part of the real object image light go toward the pupil of the user and a second surface being opposite to the first surface and into which the real object image light enters; wherein the reflective means includes a plurality of reflective units having a size of 4 mm or less that are embedded and arranged inside the optical means to transfer the augmented reality image light, transferred to the reflective means, to the pupil of the user by reflecting the augmented reality image light; and wherein at least two reflective units of the plurality of reflective units are arranged closer to the second surface of the optical means as a distance from the image output unit increases.
 2. The optical device of claim 1, wherein the augmented reality image light output from the image output unit is directly transferred to the reflective means through an inside of the optical means, or is totally reflected from an inner surface of the optical means at least once and then transferred to the reflective means.
 3. The optical device of claim 1, wherein each of the plurality of reflective units is inclined at an angle of 45 degrees or less with respect to a forward direction from a center of the pupil of the user.
 4. The optical device of claim 1, wherein, when the optical device for augmented reality is placed in front of the pupil of the user, assuming that a forward direction from the pupil is referred to as an x axis, any one of line segments being parallel to a vertical line between the image output unit and the x axis along the x axis and passing between the first and second surfaces of the optical means is referred to as an y axis and a line segment perpendicular to both the x axis and the y axis is referred to as an z axis, then each of the plurality of reflective units is formed in bar shapes extending in a z-axis direction.
 5. The optical device of claim 1, wherein at least some of the reflective units have a different size.
 6. The optical device of claim 1, wherein at least some of the reflective units are arranged at intervals different from intervals at which other reflective units are arranged.
 7. The optical device of claim 1, wherein at least some of the reflective units are composed of at least any one of half mirrors, refractive elements, and diffractive elements.
 8. The optical device of claim 1, wherein at least some of the reflective units have a surface coated with a material that absorbs light without reflecting light, wherein the coated surface is opposite surface to a surface reflecting the augmented reality image light.
 9. The optical device of claim 1, wherein at least some of the reflective units have surfaces formed as curved surfaces.
 10. The optical device of claim 9, wherein the surfaces formed as curved surfaces are concave toward the first surface of the optical means or convex toward the first surface of the optical means.
 11. The optical device of claim 9, wherein, when the reflective units are placed in front of the pupil of the user, assuming that a forward direction from the pupil is referred to as an x axis, any one of line segments being parallel to a vertical line between the image output unit and the x axis along the x axis and passing between the first and second surfaces of the optical means is referred to as an y axis and a line segment perpendicular to both the x axis and the y axis is referred to as an z axis, then at least some of the reflective units are formed such that a length thereof in a z-axis direction is formed to be longer than a length thereof in an x-axis direction or such that a length thereof in a y-axis direction is formed to be longer than a length thereof in the z-axis direction.
 12. The optical device of claim 11, wherein the reflective units formed such that the length thereof in the z-axis direction is formed to be longer than the length thereof in the x-axis direction or such that the length thereof in the y-axis direction is formed to be longer than the length thereof in the z-axis direction have surfaces formed as concave toward the first surface of the optical means or as convex toward the first surface of the optical means. 